Preparation of guanidinium mercaptoalkanesulfonate



United States Patent PREPARATION OF GUANIDINIUM MERCAPTOALKANESULFONATEApplication December 12, 1951, Serial No. 261,378

25 Claims. (Cl. 260-501) No Drawing.

This invention relates to certain novel compounds and to novel processesfor their preparation.

It is an object of our invention to prepare new and useful sulfurandnitrogen-containing organic compounds by means of the novel processesdescribed more fully hereinafter. The compounds of the invention areprepared by a novel combination of steps, some of which are also novel.The compounds, which result from the different steps will be describedmore fully hereinafter. The novel compounds are all useful asintermediates for the preparation of other compounds.

The general reactions and the compounds produced thereby may be seenfrom the following equations:

(1) X(GH2),.X MezSO: X(CHz)mSOaMe MeX where X is a halogen, preferablybromine or chlorine, n is a small whole number between 1 and 5,preferably 2, and Me is an alkali metal preferably sodium. Forconvenience, the process will be further referred to as illustrativewhen X is bromine, n is 2, and Me is sodium.

It will be appreciated that any water-soluble sulfite may be employed inReaction 1 in place of the metal sulfite shown above. Due to certaineconomic factors, sodium or potassium sulfite is usually employed. Thewatersoluble metal metabisulfites, such as sodium metabisulfite, mayalso be used in place of the sulfite in Reaction 1. However, in thelatter cases, it is necessary to add a mole of the metal hydroxide, suchas sodium hydroxide, per mole of metabisulfite.

quantities to the Reaction 1 since the presence of excess sulfite favorsthe formation of undesirable disulfonates.

Furthermore, amine compounds, other than ammonia, such as methylamine,monoethanolamine, etc., may be used in Reaction 3 above. In such casesthe product will, of course, be the corresponding substitutedguanidinium mercaptoalkanesulfonate.

Reaction 1 has been described in the literature in an article by I. M.Lipovich, J. Applied Chem. (USSR) 18, 718-24 (1945); Chem. Abs. 40, 6407(1946). In this experiment, the investigator purified a resultingbromoethanesulfonate compound and converted it with sodium hydrogensulfide (NaSH) to the sodium Z-mercaptoethanesulfonate. In an exampleemploying the haloethanesulfonate in accordance with our invention, wedo not employ sodium hydrogen sulfide but rather react the sodiumhaloethanesulfonate salt with thiourea. This process is believed to benovel. We have found that by reacting the sodium haloethanesulfonatewith thiourea It has been found advisable not to add the sulfite ingreater than SlIOlChlOIIlfitI'iC.

as in Reaction 2 above, the inner salt B-S-thiuronium ethanesulfonate isformed, together with the metal halide salt from which it may beseparated to obtain pure fl-s-thiuronium ethanesulfonate. The reactionis promoted by heating a solution of the two reactants in any inertreaction medium such as water, preferably in about molal proportions, ata temperature of from 150 F. up to a gentle boil for a period betweenabout one and three hours and allowing the solution to stand, generallyfor several hours at room temperature or lower to permit the crystallineprecipitate of the fl-S-thiuronium ethanesulfonate to deposit from thesolution. The [3-S-thiuronium ethanesulfonate may be purified byrecrystallization from water or other solvent. The purifiedp-S-thiuronium etnanesulfonate product does not possess a sharp meltingpoint but decomposes upon heating to 265 C. The p-S-thiuroniumethanesult'onate is then reacted with aqueous ammonia as in Reaction 3above to form the pure single product of guanidiniumB-mercaptoethanesult'onate which is believed to be a novel compound. Thereaction is promoted by heating the reactants in substantially molalproportions on a steam bath to promote an exothermic reaction. Atemperature of to F. may be used and the time required is about one tothree hours. Any inert solvent, preferably water, may be used. Thereaction mixture is concentrated preferably under vacuum after standingfor several hours and the residue crystallizes on cooling. The whitesalt may be recrystallized rrom anhydrous alcohol to give a wnitecrystalline product with a melting point of 109-172 C.

The literature contains examples of treatment of bromides and iodides ofthiuronium compounds with ammonia or amines to yield mercaptans andguanidines. This is to be'distinguished from the reaction of thiuroniumcompounds of the inner-salt type such as ,B-S-thiuronium etnanesulronatein accordance with theinvention. We have found the reactions reportedheretofore do not occur when the inner salt is used; but, on the otherhand, a novel reaction is obtained which produces a single additionproduct containing a guanidinium radical, not previously prepared.

The guanidinium compound is especially useful as an intermediate in thepreparation of other chemical compounds, and due to the fact that it isformed by the present process without any contaminating impurities orextraneous products, the preparation and recovery of its derivatives aregreatly simplified. In most instances, the resulting guanidiniumcompound may be used as formed in the reaction without furtherpurification.

The guanidinium mercaptoalxanesulfonate product of Reaction 3 above maybe converted to the corresponding salts of other bases by one of severalmethods. For example, it may be converted by means of the doubledecomposition with a nitrate salt such as ammonium or sodium nitrate,taking advantage of the low solubility of guanidine nitrate which isformed by the double decomposition reaction in which the guanidiniumradical of the guanidinium sulfonate salt is replaced. However, a moresatisfactory process which also permits the preparation of the freesulfonic acid is by means of a cation resin exchange treatment in whichan aqueous solution of guanidinium mercaptoalkanesulfonate is passedthrough a cation exchange resin whereby the guanidinium ion is replacedby a hydrogen ion to form mercaptoalkanesulfonic acid in accordance withthe reaction:

9 HS(CHi)nSOaNHr-C H(lon resin) 7 NH: guanidiniummercaptoalkanesulfonate NH; I HS(CHa),.SOaH C=NHI(1OD resin) N amercaptoalkanesuliom'c acid where n is a whole number.

Any cation exchange resin possessing strongly acid groups issatisfactory for use in converting the guanidinium sulfonate salt intothe corresponding sulfonic acid. Examples of suitable cation resinexchange materlals are the nuclear sulfonic type cation resins such asthe commercial Amberlite lift-120, Arnberlite iR-lOO, and Dowex50' whichare corrimercially available on the market.

1 The mercaptoalkanesul-fonic acid obtained will be extremely pure, animportant factor because the oxidationor mercaptans is catalyzed by thepresence of small amounts of impurities. The acid can be useddirectly-in the preparation or" derivatives of the sulfonic acid. Forexample, the sulfonic acid may be reacted with various basic compoundsto form the corresponding salts. For example, mercaptoe'thanesulfonicacid can be reacted with monoethanolamine in an addition reaction toprepare monocthanolamine B-mercaptoethanesulfonate as follows:

HSCHzCHzSOsH+H2NQH2CH2DH I HSGHzCH2S0sNI-I3CH2CH2OH in a similaraddition react-ion fl-mercaptoethanesulfonic acid can be reacted withethylamine to form the corresponding ethylamine B-rnercaptoethanesulfonate as fol' lows:

HSCHzCHzSCaH-I-QhiaCHNHt-X I-lSCHzCHzSOBNHsCH2CH3v Themercaptoalkanesul'fonic acids can also be reacted with mineral bases toform corresponding saltsofthe sulfonic acid by a substitution reaction.One example thereof is the reaction of sodium hydroxide withp-mercaptoethanesulfonic acid to prepare sodiumB-mercaptoethanesulfonate as follows:

HSCHzCHzSOsl-I+Na0H HSCI-lzCI-IzSOsNa+HzO Similarly ammonium hydroxidecan be reacted with 18- mercaptoethanesulfonic acid to prepare ammoniumniercaptoethanesulfonate by the following reaction:

uscnzcnzsosuq-umons ..t,. compound through cation exchange resinspossessing in place of the reactive hydrogen -ion some other labilecation group. i

The utility of the present invention in preparing the novel compoundsand their derivatives as described above is readily apparent. Thecompoundsin each instance are easily obtained very pure andv wherepurification is re quired, it is a simple matter of recrystallizationfrom a suitable solvent such as water or alcohol. A comparison, forexample, of the preparation of the sodium B-r'ncrcaptoethanesulfohatesalt from the pure gu'anidinium B mercaptoethanesulfohate salt asdescribedaboveis much simplified over the process for obtaining the samesodium sulfonate salt by the method described in the Lippvich articleabove. The following examples are illustrative of I the present processbut are, not intended to be limiting thereof:

EXAMPLE 1 flask was filled with 2460 g. of ethylene dibromide, 5000 cc.of 95% ethylalcohol and1800 cc. of water. The mix-.

ture was heated to a vigorous reflux and while being stirred, there wasadded a solution of 500 g. of sodium sulfite in 1800 cc. of water over aperiod of Shouts. The refluxing was continued until the reaction wassubstantially complete. At the end of this time, the mixture wasdistilled until 5 litersv of solution had been removed. 1500 g. ofethylene dibromide was recovered from the distillate. The residualsolution was poured into large evaporating dishes and taken to drynesson the steam bath. From this there was obtained 1 182 g. of whitecrystalline material of sodium B-bromqethanesulfonate containing 32 .8%sodium bromide.

Six h 'ndred grams of the sodium ,G-bromoethanesulfonate-sodiurn bromidemixture, 155 g. of thiourea, and

500 cc. of water. were heated in a 2-liter beaker on an electric hotplate until solution was effected. A hot filtration removed suspendedextraneous material after which the clear solution was heated to agentle boil for an additional hour. At the end of this time the solutionwas allowed to stand at room temperature overnight. In this way, therewas obtained 230 g. of B-S-thiuronium ethanesult'onate as a crystallineprecipitate, which was recrystallized from water. This represents a 65%yield based on ethylene dibromide. The compound does not possess a sharpmelting point but was decomposed upon heating to 265 C.

The above experiment was repeated with satisfactory results by placingthe same total quantities of ethylene dibromide, alcohol, water, andsodium sulfite together in the flask and refluxing the mixture for onehour and then allowing the reaction mixture to distill until theresidual solution was concentrated to 1 /2 liters. The unreactcdethylene dibromide was recovered from the distillate.

EXAMPLE 2 Guanidinium B-merc'aptoethanesulfonatefi-Two. hundred andthirty gramsof ,B-S-thiujrbnium ethanesulfonate was placed in a 1-literround-bottom flask. To this there was added 500 cc. of concentratedaqueous ammonia, and the reaction mixture was heated on the steam bath.An exothermic reaction ensued within a short time at which point thereactionwas removed from the steam bath and allowed to stand at roomtemperature. After standing for 2 hours, the solution was concentratedin. vacuum until all of the water had been removed. The residuecrystallized upon cooling and the white solid was recrystallized fromanhydrous alcohol. The yield of dried product was 118 g. with a purityof 96.5% as determined by SH content. 'lhis represents a 30% yield basedupon sodium sulfite. An additional 69 g. of material with a purity of7.6% was recovered from the filtrate. This. gives a total yield of 187g. or 48% based upon sodium sulfite. The melting point of the purematerial wa 169-172 C;

EXAMPLE 3 B-Mercaptoethanesulfonic acid.0ne hundred gramsofiB-S-thiuronium ethanesulfonate prepared as in Example 1 wasreactedwith 200 cc. of concentrated aqueous ammonia as in Example 2. The excessammonia was re- EXAMPLE 4 fi-S-thiuron'ium ethhnfesu'lfo'izdt erfThe.experiment of. Example 1 was repeated with the modification that aftercompletion of refluxing, the solution was concentrated. to 1 liters.This solution wasreacted directly with 306 grams o fvthiourea, Afterstanding ov'ernight, 415. grams of. [3 -S-thiuroniu rn ethanesulfonatewere recovered. The proportions of materialused in thisexperimcnt arefound to be most desirable inasmuch as the maximum amount dS-thiuroniurnethanesulfonate is recovered contaminated with a minimum;amount (about0.2 sodium bromide. The use of more water than specified results in adecreased yield offl-S-thiuronium, ethanesulfonate while moreconcentrated solutions tend to; increase the sodium bromide content.Under the pi' e ferred;r ea ction condio he. reaction. pro uct, may. be..6 irectly it out purification injthe preparation of the; sul-fonic;acid1 asin Example- 3 and in the production of derivative prod ucts.

EXAMPLE, 5:

B-Mercaptoethanesulfonic acid. 2;1'00 grams of 5-5;. thillroniurethanesulfonate were; placed 'ina solutionof, 2,1G0 cc. of concentratedaqueousammonia and 400 cc. of water. The mixture was carefully warmed on:asteam. bath andan exothermic reaction yensued. at; which point; theB-S-thiuroniumethanesultonate passed. into -.solut i qn.- After standingfor two hours at room temperature, the

' droxide.

solution was concentrated until all of the excess ammonia had beenremoved. I

The resultant clear solution from the ammonolysis reaction was processedthrough Amberlite lR-120 ion exchange resin and converted intofl-S-mercaptoethanesulfonic acid in 93.7% yield (based on p-S-thiuromumetnanesulfonate) It is expedient not to heat the reaction mixturerapidly since this increases the loss of ammonia and effects anincomplete reaction. Heating the mixture too rapidly may retard theammonolysis reaction entirely. The amount of ammonia used is consideredto be a sat1sfactory minimum and larger quantities of ammomaare notfound to have any beneficial effect on the reaction. It is alsoexpedient to remove the excess ammonia before processing the guanidiniumB-mercaptoethanesulfonate solution through the ion exchange resin sincethe resin will also remove the ammonia with the result that the capacityof the resin for the exchange of guanidinium ions will be reduced.

Although the preparation of fi-mercaptoethanesulfonic acid through theammonolysis reaction is the preferred method, it is also possible toprepare the sulfonic acid-by the sodium hydroxide hydrolysis offi-S-thiuronium ethanesulfonate followed by the ion exchange treatment.The resulting acid, however, is generally not as satisfactory as thatprepared by the ammonolysis reaction.

EXAMPLE 6 B-S-thiuronium ethanesulfonate .-In another experiment similarto Example 1, 1300 grams of ethylene dichloride were reacted with 625grams of potassium sulfite in a solution of 5000 cc. of 95% ethylalcohol and 3600 cc. of water. From this reaction, there was obtained a65% yield of potassium B-chloroethanesulfonate. A concentrated solution(1 /2 liters) of the reaction mixture was mixed with thiourea and heatedwith Water until solution was eifected. The solution was gently boiledfor an additional hour and allowed to stand at room temperatureovernight. Crystalline fi-S-thiuromum ethanesulfonate was isolated fromthe reaction mixture in 41% over-all yield based on the potassiumsulfite.

EXAMPLE 7 'fl-mercaptoethanesulfonate as a clear colorless syrup. The

yield was 30 g.

EXAMPLE 8 Ethylammonium 18 mercaptoethanesulfonate. An aqueous solutioncontaining 21 g. of jB-mercaptoethanesulfonic acid was neutralized with6.6 g. of ethylamine. The product after vacuum concentration wasobtained as a semi-crystalline solid.

EXAMPLE 9 Ammonium ,B-mercaptoethanesulfonate.Twenty-one grams ofB-mercaptoethanesulfonic acid were neutralized with 5.1 g. of ammoniumhydroxide as above. A quan titative yield of ammoniumfi-mercaptoethanesulfonate was obtained. After recrystallization fromalcohol the material melted at 1585-1635 C.

EXAMPLE 10 Sodium B mercaptoethanesulfonate.-Twenty one grams ofB-mercaptoethanesulfonic acid were converted into the sodium salt byneutralization with sodium hy- This compound after recrystallizationfrom ethyl alcohol did not possess a melting point upon heating to 250C.

EXAMPLE 11 Ammonium ,8 mercaptoethanesulfonate. Twenty grams ofguanidinium B-mercaptoethanesulfonate was dissolved in 10 cc. of waterand to this was added 8 The ion col- Vacuum concentration of the EXAMPLE12 Sodium fl-mercaptoethanesulfonate.-The procedure of the previousexample was repeated except that 8.5 grams of sodium nitrate is employedinstead of ammonium nitrate.

It will be obvious that our invention may be modified in accordance withthe practices known to those skilled in the art. The above descriptionis intended to set forth the best mode of practicing our invention andnot as limitative thereof except as required by the following claims.

We claim:

1. A process for the preparation of S-thiuronium alkanesulfonate whichcomprises reacting an alkylene dihalide with an alkali metal sulfite atan elevated temperature, removing unreacted dihalides, adding thiourea,heating until solution is elfected, allowing the reaction mixture tostand, and recovering a crystalline precipitate of said S thiuroniumalkanesultonate.

2. A process for the preparation of B-S-thiuronium ethanesulfonate whichcomprises reacting ethylene dihalide with an alkali metal sulfite atrefluxing temperature, removing unreacted halide, adding thiourea,heating until solution is effected, allowing the reaction mixture tostand at room temperature, and recovering a crystalline precipireacteddihalide, adding thiourea, heating the second mixture again untilreaction is effected to form S-thiuronium alkanesulfonate, addingconcentrated aqueous ammonia and heating the mixture, concentrating thesolution, and recovering said guanidinium mercaptoalkanesulfonate.

5. A process for the preparation of guanidiniumfimercaptoethanesulfonate which comprises reacting ethylene dihalidewith an alkali metal sulfite in an alcoholwater solution, refluxing themixture, removing unreacted dihalide, adding thiourea, heating thesecond mixture again until the solution is clear, separating a resultingcrystalline precipitate, adding concentrated aqueous ammonia to saidprecipitate and heating the mixture to boiling, allowing the reactionmixture to stand at room temperature for several hours, concentratingthe solution in vacuum to remove the water, cooling the concentratedsolution recrystallizing a final resulting precipitate with anhydrousalcohol and recovering said guanidinium B-mercaptoethanesulfonate.

6. A process of preparing a guanidinium mercaptoalkanesulfonate whichcomprises reacting an S-thiuronium alkanesulfonate with a compoundselected from the group consisting of ammonia and an amine.

7. A process of preparing a salt of a mercaptoalkanesulfonic acid whichcomprises reacting an alkylene dihalide with an alkali metal sulfite toform a haloalkanesulfonate, reacting said haloalkanesulfonate withthiourea to form an S-thiuronium alkanesulfonate, reacting saidS-thiuronium alkanesulfonatewith a compound selected from the groupconsisting of ammonia and an amine to form a guanidiniummercaptoalkanesulfonate, and converting said guanidiniummercaptoalkanesulfonate to a salt of a mercaptoalkanesulfonic acid.

8. A process of preparing a salt of a mercaptoalkanesulfonic acid whichcomprises reacting a haloalkanesulfonate with thiourea to form aS-thiuronium alkanesulfonate, reacting said S-thiuronium alkanesulfonatewith a compound selected from the group consisting of ammonia and anamine to form a guanidinium mercaptoalkanesulfonate, and converting saidguanidinium mercaptoalkanesulfonate to a salt of amercaptoalkanesulfonic acid.

9. A process according to claim 7 in which the guanidiniummercaptoalkanesulfonate is converted to a salt of amercaptoalkanesulfonic acid by reaction with a nitrate salt.

10. A process according to claim 7 in which the ,salt not:la-s1nerc:aptoalkanesulfoniciacidshy;

change resin to form a mercaptoalkanesulfqtt cgacid,:and reacting saidsulfonic acid :with-a basic compound.

11. A process according to claim 7 in which the yguanidiniummercaptoalltanesulfonate is converted ,to a salt of amereaptoalkanesulfonic acid by ,passing theguanidinium.mercaptoalkauesulfonate over a cation exchange resinhavinga'labile cation group other than hydrogen.

' 1T2.,"A, .process v or; [preparing 7 a ,mercaptoalkanes'ulfonic acidwhich comprises reacting.ahaloalkanesulfonate with ithiourea to'form aSthiuroriiu'm alkanesulfonatejreactling. said'S-thiuroniumalkane'sulfonate with a compound selected'from the group consisting ofammonia and an amine to form a guanidinium mercaptoalkanesulfonate, andpassing said guanidinium mercaptoalkanesulfonate over acationexchangejresintoform a mercaptoalkanesulfo'nicia'cid. p

13. r A process of preparingjjguanidinium fi mercapto- 'ethanesulfonatewhich'comprises' reacting B S-thiuron'ium ethanesulfonate with ammonia.

' 14." As a'new composition of matter, ,guanidiniummercaptoalkanesulfonate of "the "followin g .fgen'eral formula:

1-,N'H2 nszcrmtsot nnz d final where-wris 1 to 5.

15. As a newcompositionofirnatter;guanidiniumfflmereaptoethanesulfonateof the following formula:

VNH:

HSCH:C-H:&O:' NHz- C I NH:

addingconcentrated-aqueous -ammoniato the precipitate and heating the=mixture to --boiling,- allowing the reac- 'tion-'miXture-' -to stand atroom temperature for several hours, concentrating the solutionin -vacuum'toremove 'the water, cooling the concentrated solution, andreplacing'the guanidinium radical ofthe; resulting compound witcllihydrogen --'toform S8.id fi-mercaptoethanesulfonic act 18. The process according toclaim 17 in which said crystalline guanidinium B-mercaptoethanesulfonate-is passed'in aqueous solution overa body of-ca'tion exchange'resin tofrom said fi-mercaptoethanesulfonicacid.

l9. A process according toclaim 18 in which said cation exchange resinis t a nuclear sulfonic type ion exchange resin.

1:20am;process-toreithespreparation-,ofnmonoethanolam moniurn'fl-mercaptoethanesulfonate which comprises rea ingrethylen ,dihalide-Wthtam lkali; 5 31.- ulfitein n alcohol-water solation, refluxing the 7mixture, removing nnreacted dihalide, adding thiourea, heating the.second mixturemntil; the/solution; is clear, separating aresultingcrystalline precipitate, adding concentrated aqueous ammoniato theprecipitate and heatingthe mixture to boiling, 'allowing the reactionmixture to stand at room temperature forvseveral, hours, concentratingthe solution inrvacuum rto remove waten cooling the concentratedsolution, massing the concentrated aqueous solution through'a cationexchange resin, andneutralizing the efiiuent acidic-solutionlwithimonoethanolamine to obtain :said -monoethanolammoniumfi-mercaptoethanesul- .fonate.

-;-21. A processior wthepreparation of'sofdium fi-mercaptoethanes'ulfonate :which comprises reacting ethylene .dihalide.withian alkali metal r-sulfitelin an alcohol-Water solution, refluxing"the mixture, .removing Iunreactred .dihalide, "adding ,thiourea, Vheating the second ture until rhe;solution isielear, separatingia"resulting ,crystalline precipitate, adding 'concentrat'e'd'aqueousiflm- ,monia to "the precipitate andyheating the fmixture 'toboiling, allowing the reaction mixture to *stand "atjroom temperaturefforjseveralhours, concentrating the solution' in vacuum to '"remove'waterfcooling ithe-concentrated solution, passingthe concentratedaqueous solution through a cation "exchangezresin, and neutralizing theefiiuent acidic, solution with sodium hydroxide to obtain ,said' sodiumfi-mercaptoethanesulfonate.

22. A process for the preparation ot ammonium "B-mercaptoethanesulfonate which comprises reacting eth- -ylenedihalidewithan alkali metal sulfitein analeohol- Water: solution 'refluxing themixture, removingunreact- 'ed dihalide,-addin g thiourea, heating thesecond mixture until the-solutionis clear, separating a resultingcrystalline precipitate, addingconcentrated aqueous ammonia to theprecipitate and heating 'the mixture to (boiling, i'allowing thereaction'mixture to stand at room temperature for several ho'urs;concentrating the solution in avacuurn to remove the watergcooling theconcentratedisolution, passing the concentrated :aqueous solutionthrough a cation exchange resin, and neutralizing the efiiuent acidicsolution with ammonium hydroxide to obtain said am- -moniurn-.fl-mercaptoethanesulfonate.

r23 A:process :f0r. the preparation of a mercaptoalkane- ;sulfonate:whichcomprises passing guanidin'ium mercaptoethanesulfonate over, acation-exchange resin possessing a labile:cation,jgroup.

24. A, process iof -preparing a,--saltof =B-mercaptoethanesulfonicgacid-the cation of which- .forms avsolubletnitrate, which comprises:reactingyguanidinium-fl mercaptoethanesulfonate :with saidsoluble-nitrateofsaid,cation :to form said salt offl-mercaptoethanesulfonate and ,guanidine nitrate-which .is;precipitated.

, 25. A process of preparing ammonium fi-mercaptoethanesulfonate, whichcomprises reacting guanidiniumrflmercaptoethanesulfonate with ammoniumnitrate to form ammonium ,B-mercaptoethanesulfonate and relativelyinsolublejguariidine nitrate.

, ReferencesCited-in :the"fi-le"of this patent UNITEn'sTATEs' PATENTSNumber Name Date 1,888,794 Ernst et a1 Nov. 22, 1932 2,459,440 Lieber'eta1. Janf18, 1949 2,559,585 "Becket al '-*July- 10, 1951

1. A PROCESS FOR THE PREPARATION OF S-THIURONIUM ALKANESULFONATE WHICHCOMPRISES REACTING AN ALKYLENE DIHALIDE WITH AN ALKALI METAL SULFITE ATAN ELEVATED TEMPERATURE, REMOVING UNREACTED DIHALIDES, ADDING THIOUREA,HEATING UNTIL SOLUTION IS EFFECTED, ALLOWING THE REACTION MIXTURE TOSTAND, AND RECOVERING A CRYSTALLINE PRECIPITATE OF SAID S-THIURONIUMALKANESULFONATE.